Mann-Kendall Trend Test
Computes the Mann-Kendall test, used to detect a monotonic trend (upward or downward) in a time series without assuming the data are normal or the trend is linear. It sums the signs of all pairwise comparisons between values: if the series tends to rise over time, positive signs prevail. It's widely used in hydrology, climatology and environmental science to assess trends in long series. The S statistic becomes a z via the normal approximation, with a tie correction. Enter the series in chronological order.
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Mann-Kendall Trend Test
Computes the Mann-Kendall test, used to detect a monotonic trend (upward or downward) in a time series without assuming the data are normal or the trend is linear. It sums the signs of all pairwise comparisons between values: if the series tends to rise over time, positive signs prevail. It's widely used in hydrology, climatology and environmental science to assess trends in long series. The S statistic becomes a z via the normal approximation, with a tie correction. Enter the series in chronological order.
Is there a trend, even when the series misbehaves?
Environmental series — river flow, temperature, pollutant concentration — are rarely normal and almost never rise in a straight line. Even so, the question of whether there is a long-term trend remains. The Mann-Kendall test was made for this: it detects a monotonic trend without requiring any specific shape for the data.
The mechanism is to compare each value with all those that came after it and count the signs. Each time a later value is larger, it counts plus one; when smaller, minus one. If the series rises over time, positive signs dominate and the S statistic sits well above zero. Because S depends only on order, extreme values don't distort it, and a normal approximation converts S into a z score with a tie correction.
Enter the series in the order it was observed in time. The tool returns S and the z score, from which the p-value follows. Note that the test detects a trend but doesn't quantify it — to estimate the magnitude of the slope in an equally robust way, the natural companion is the Theil-Sen estimator.
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Friedman Test
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Wilcoxon Signed-Rank Test
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The results provided by this tool are for general informational and educational purposes only and do not constitute professional, financial, medical, legal, tax or accounting advice. Always confirm important decisions with a qualified professional and official sources.